I have a function which allocates 2D matrix at the start and a function which deallocates it, which I use at the end.

int** CreatMat(int N){
    int i,**T;
    T = (int**)malloc(sizeof(int*)*N);
    if(T!=NULL){
        for(i=0;i<N;i  ){
            T[i]=(int*)malloc(sizeof(int)*N);
            if(T[i]==NULL){
                printf("\nCreatMat()::Allocation failed at block %d",i);
                for(i=i;i>=0;i--){
                    free(T[i]);
                    T[i]=NULL;
                }
                free(T);
                T=NULL;
                return T;
            }
        }
    }
    return T;
}

//Free a dynamic matrix.
void FreeMat(int** T,int N){
    int i;
    for(i=0;i<N;i  ){
        free(T[i]);
        T[i]=NULL;
    }
    free(T);
    T = NULL;
}

Somehow, FreeMat() is crashing. any help?

Full code here

CodePudding user response：

In function main() this

int **T, **S;
if(Grids_Init(T, S) != 0)

does not affect the value of the local variables S and T which remain uninitialised, and you then go on to free these indeterminate pointers.

You can use a function to initialise one of them, return the pointer and assign it to T. Then same for S.

This is preferable to using the three-star pointers: please see Triple pointers in C: is it a matter of style? One answer begins with

Using triple pointers is harming both readability and maintainability.

CodePudding user response：

You do not create 2D array only an array of pointers. Make your life easier and locate a real 2D array. Also, use the correct type for sizes size_t

void CreatMat(size_t N, int (**array)[N])
{
    *array = malloc(N * sizeof(**array));
}

int main(void)
{
    int (*array)[N];
    CreatMat(1000, &array);

    /* some code */

    free(array);
}

See how much easier it is.